Brain Scans Reveal Why People Become Aggressive After Drinking Alcohol

Through the utilization of Magnetic Resonance Imaging (MRI) scans, researchers are able to measure blood flow in the brain to better understand why people become aggressive and violent after consuming alcohol. Research notes significant changes in the working of the prefrontal cortex of the brain after two drinks – a part of the brain that tempers an individual’s aggression levels. This study was conducted by Thomas Denson of the University of New South Wales in Australia, and was published in the journal of Cognitive, Affective, & Behavioral Neuroscience.

Fifty healthy young men participated in the study. They were either given two drinks containing vodka, or placebo drinks without any alcohol. Participants then had to compete in a task which has regularly been used over the past decade to observe levels of aggression in response to provocation, whilst lying in an MRI scanner.

The functional magnetic resonance imaging allowed Denson and his team to identify which areas of the brain were triggered when the task was performed. They were also able to compare the difference in scans between participants who had and had not consumed alcohol. Being provoked was found to have no influence on participants’ neural responses. However, when behaving aggressively, there was a dip in activity in the prefrontal cortex of the brains of those who had consumed alcoholic beverages.

“Although there was an overall dampening effect of alcohol on the prefrontal cortex, even at a low dose of alcohol we observed a significant positive relationship between dorsomedial and dorsolateral prefrontal cortex activity and alcohol-related aggression,” states Denson. “These regions may support different behaviors, such as peace versus aggression, depending on whether a person is sober or intoxicated.”

The results are vastly consistent with a growing body of research about the neural basis of aggression, and how it is triggered by changes in the way that the prefrontal cortex, the limbic system and reward-related regions of the brain function. The results of the current study are also consistent with several psychological theories of alcohol-related aggression.